Robustness Research Of Urban Metro-Bus Coupling Network Based On Complex Network

With the continuous development of transportation,the urban transportation system is no longer a single system,but consists of multiple systems.The urban transportation system with the subway and bus network as the main body has greatly improved the travel efficiency of the urban population and the diversity of residents’ travel modes.It improves the overall transportation capacity of urban traffic.Subway and bus networks play a vital role in the development and construction of urban transportation,and are of great significance to the optimization of modern urban transportation functions and the construction planning of future transportation networks.Based on the complex network theory,this paper establishes a subway-transit coupled network model,analyzes the complexity and survivability of the network,comprehensively evaluates the importance of nodes in the network,and gives an optimal recovery strategy for rapid recovery of the network,which improves the recovery efficiency of the network.,to improve the operation capacity of the subway-transit coupling network.The specific research contents are as follows:First,the Space L method is used to construct the subway network and bus network and the subway-transit coupled network model.A comparative analysis of the three network characteristic indicators is carried out.Taking Dalian as an example,the Dalian subway-bus coupling network model is constructed,and the network complexity and survivability are analyzed.The research shows that the Dalian subway-bus coupling network conforms to the characteristics of scale-free network and small world network.The characteristic indicators of the coupling network have been optimized to varying degrees,which has resulted in a certain improvement in the accessibility of the urban transportation network,and the network performance has been significantly optimized and improved.Second,a node importance evaluation algorithm(SOW method)based on subjective and objective integrated weighting is given,and an evaluation index system is constructed to prevent the cascading failure of the network,prioritize the protection of important sites in the coupled network,and improve the network survivability.Combined with the multi-index comprehensive evaluation method in decision theory,on the basis of classical index evaluation,the subjective and objective weighting method is introduced to evaluate the importance of network nodes.The results show that the subjective and objective weighting method is more accurate than other classical node evaluation algorithms.It evaluates the importance of nodes from multiple dimensions,and can find important sites for protection and repair in advance when the network fails,which improves the invulnerability of the network.Reduce the loss of public property and ensure the personal safety of passengers.Thirdly,in order to improve the recovery speed after network failure,an optimal repair strategy based on the important critical nodes of the giant branch of the network is given.In the conventional repair method,the critical nodes of the network giant branch and the SOW method given above are used to evaluate the important critical nodes of the network,and the critical nodes with the greatest importance are found for priority restoration.The existence probability of the largest connected subgraph after the network is damaged and the number of steps for the network to reach a stable state are used as the evaluation indicators for the effect of network recovery.The optimal network restoration strategy not only reduces the time required to restore the network,but also reduces the energy efficiency loss of the coupled network,effectively alleviates the cascading diffusion of the urban transportation network,and prevents the network from collapsing to a greater extent.